Self-cleaning air flow bar for apparatus for making aggregate

ABSTRACT

A self-cleaning air flow bar in a traveling grate assembly for conveying carbonaceous shale and the like through a furnace to make lightweight aggregate, including a series of self-cleaning air-flow bar members, with a first said bar member extending transversely across the traveling grate assembly and including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, a second self-cleaning air-flow bar member extending transversely across the grate assembly and including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, said first bar member rearwardly extending key portions positioned in the spaces between the second bar member forwardly extending key portions, whereby, when the grate assembly travels around a sprocket, the key portions of one cross bar wipe clean the spaces between the key portions of the other cross bar.

United States Patent [1 1 Connell Feb. 5, 1974 SELF-CLEANING AIR FLOW BAR FOR APPARATUS FOR MAKING AGGREGATE [76] inventor: John G. Connell, 232Wyoming Ave., West Pittston, Pa. 18643 [22] Filed: Apr. 10, 1973 [21] Appl. No.: 349,711

Primary ExaminerJohn J. Camby Attorney, Agent, or FirmJohn F. A. Earley 1571 ABSTRACT A self-cleaning air flow bar in a traveling grate assembly for conveying carbonaceous shale and the like through a furnace to make lightweight aggregate, including a series of self-cleaning air-flow bar members, with a first said bar member extending transversely across the traveling grate assembly and including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, a second selfcleaning air-flow bar member extending transversely across the grate assembly and including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, said first bar member rearwardly extending key portions positioned in the spaces between the second bar member forwardly extending key portions, whereby, when the grate assembly travels around a sprocket, the key portions of one cross bar wipe clean the spaces between the key portions of the other cross bar.

10 Claims, 12 Drawing Figures PATENIEBFEB 51914 $790,337

mm u (1F 5 FIG. 6.

7H; 7 m N F I, mf a :2: #1 a W 222 mm L" 5 I m m m n F F d 5% a Q m l SELF-CLEANING AIR FLOW BAR FOR APPARATUS FOR MAKING AGGREGATE CROSS-REFERENCE TO RELATED PATENT This application relates to a self-cleaning air-flow bar for use with apparatus for making aggregate such as that disclosed in my U. S. Pat. No. 3,260,513, which issued on July 12, 1966, and is incorporated herein by reference.

I BACKGROUND OF THE INVENTION This invention relates to apparatus for making lightweight aggregate such as used in making blocks for building construction and in making heat-insulating materials, or used in sludge beds in sewage disposal plants, or used in structural concrete in high-rise buildings, or used in fabricated floor panels and roof panels, and more particularly concerns a self-cleaning air-flow bar for such apparatus. I In a furnace or apparatusfor making lightweight aggregate, such as the apparatus disclosed in my U.S. Pat. No. 3,260,513, a traveling grate supports material to be burned and includes a series of transverse grate bars. Each transverse grate bar is about 13 feet across and supports about 155 keys 8 inches long with openings between keys for the passage of air therethrough. Such air passage is necessary for proper combustion of the material to be burned.

In the conventional traveling furnace grate, the air passes upwardly at all times and this upward action of the air keeps the grate air holes or openings clear and clean. However, in the traveling grate of Connell U.S. Pat. No. 3,260,513, the air passes downwardly through the grate in the ignition chamberand this causes conventional air openings or slots between keys to become clogged and contaminated with shale particles and with acid formed by chemical reaction in the furnace. This closing of air slots disrupts and restricts the air pattern in my combustion chamber. At times, the air slots become clogged to such an extent that they are impossible to clean, and the keys of adjacent grate bars become attached to each other, become inflexible, and break. Sometimes the keys become so solidly attached to each other that not only do the keys break, but also the grate bars supporting the keys.

Conventional keys are cast from nickel-iron alloys and are expensive to make and replace.

In conventional equipment, the up-draft of air in the furnaces cleans the fines from between the conventional cast iron keys. In the down-draft furnace of my U.S. Pat. No. 3,260,513, after the apparatus is running for a time, such keys corrode and fasten together so that you cannot jiggle them and so that the only openings in the traveling grate are the openings between the grate bars.

In attempting to solve the problem of how to clean conventional grate-bar keys inmy down-draft furnace, I tried all the cleaning methods that I knew or had ever heard of. For example, I tried cleaning the keys with steam, using a steam jenny such as those used to clean automobile motors by subjecting the motor to a jet of steam. This approach cleaned the keys to a shiny condition, but failed its purpose because it did not open the, air holes. I have also tried, unsuccessfully, to clean the keyswith compressed air, and to separate the keys and knock the dirt out of the air holes by hitting them with a sledge hammer.

A conventional traveling grate in my furnace is 110 feet long (a 55 foot long top travel path and a 55 foot bottom return path), 155 keys wide, with each key SUMMARY OF THE INVENTION Accordingly, it is an object of this invention to provide a solution to the problem of grate bar keys corroding and freezing together, breaking, and causing the breaking of grate bars,

This problem has been solved by providing a selfcleaning grate bar member having keys which automatically clean themselves when passing around sprockets. The present invention provides inexpensive, selfcleaning keys. One embodiment includes a series of spaced-apart keys having forwardly andrearwardly extending key portions connected by an overlapping portion which is welded to the base of a channel by welds running along the corners formed between the keys and the channel flanges. Another embodiment includes a series of spaced-apart forward keys welded onto a steel cross bar alternately with a series of rearward keys.

- Besides solving the problem of key breakage, the new grate bar member significantly reduces the weight of the traveling grate.

Although temperatures in the ignition chamber reach 2,600F., the carbonaceous shale material to be burned is moving with the traveling grate so that this ignition temperature heat penetrates only 1% inches of the 2% inches deep material. This leaves a one'inch protective blanket of unburned material protecting the grate from the ignition heat.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1B is a view in section taken as indicated by the lines and arrows lB1B in FIG. 1A;

FIG. 2 is a transverse view in elevation of a grate cross bar taken as indicated by the lines and arrows 2-2 which appear in FIG. 1A, with the grate bar keys removed for clarity;

FIG. 3 is a view in vertical longitudinal section of my aggregate making apparatus, and is taken from FIG. 3 of my U.S. Pat. No. 3,260,513 of July 12, I966;

FIG. 4 is an enlarged view of the left end of FIG. 2; FIG. 5 is an enlarged view of the left middle of FIG. 2;

FIG. 6 is a side elevation of an attachment member which forms a part of my grate bar member;

FIG. 7 is a view in transverse elevation of the attachment member of FIG. 6;

FIG. 8 is a partial view in perspective of a driving chain used to drive the traveling grate.

FIG. 9 is a partial view in top plan of a presently preferred embodiment of traveling grate constructed in accordance with this invention;

FIG. 10 is a view in section taken as indicated by the lines and arrows 10-10 which appear in FIG. 9; and

FIG. 11 is a partial view in elevation and partly in section taken as indicated by the lines and arrows 11-ll which appear in FIG. 9.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Although specific terms are used in the following description for clarity, these terms are intended to refer only to the structure shown in the drawings and are not intended to define or limit the scope of the invention.

Turning now to the specific embodiments of the invention selected for illustration in the drawings, there is shown in FIG. 3 a storage bin 201 for shale or raw aggregate of semi-combustible material. A rear feed passageway 202 feeds the shale through a rear feed storage bin 203 onto the surface of traveling grate 204. A vertically adjustable rear gate 205 determines the height or thickness of a sealing layer 206 of shale which is carried forwardly by traveling grate 204 through a rear opening 207-to an ignition chamber 208 which is located immediately ahead of rear gate 205. Flames from ignition means such as burners 211 are directed into ignition chamber 208, and an exhaust conduit 212 is located on each side of the furnace for carrying off the hot gases generated in the ignition chamber 208 and relieving the pressure generated therein. In this regard, sealing layer 206 plays an important role in sealing rear opening 207 against the escape of hot gases and other material.

A front feed passageway 213 extends downwardly from storage bin 201 to a front opening 214 of exhaust chamber 208 and is defined by ignition chamber leveling gate 215 and front leveling gate 216. Leveling gate 215'is vertically adjustable so as to vary the size of front opening 214, and front leveling gate 216- is vertically adjustable to vary the size of opening 217.

Conduit 212 extendsfrom ignition chamber 208 to an inlet port 221 in combustion chamber 218.

Ignition chamber 208 is completely enclosed by side walls, burner blocks 222 and roof sections 223, 224.

Similarly, combustion chamber 218 is completely en closed by side walls and roof sections 225.

Forced air emanates from air chambers 226 positioned beneath the top run of traveling grate 204 and passes upwardly through the layers of shale to assist in their burning.

A dribble chamber 227 is also positioned beneath the top run of traveling grate 204. Dribble from sealing layer 206 passes through traveling grate 204 into chamber 227. A screwconveyor 228 is provided to clean out the dribble from chamber 227.

The shale deposited on traveling grate 204 through rear opening 207 forms a sealing layer 206 which protects the grate from the high temperatures of the ignition chamber 208. The shale fed through front feed passageway 213 passes through opening 214 into ignition chamber 208 and forms a'pilot layer 231 which is 4 pre-ignited in ignition chamber 208 by the flame from ignition means such as burners 211 and is then rolled under a non-ignited layer 232 of shale by the action of traveling grate 204 and sealing layer 206 moving forwardly. The three layers pass into combustion chamber 218 through opening 217. All three layers are burned in combustion chamber 218.

FIG. 1A shows a view in partial top plan ofa traveling grate 231 for conveying carbonaceous shale and the like through the furnace of FIG. 3 to make lightweight aggregate. Grate 231 is constructed in accordance with the present invention and replaces traveling grate 204 which is of conventional construction. FIG. 1A shows a series of self-cleaning air-flow bar members including a first bar member 233 and second bar member 235. First self-cleaning air-flow bar member 233 extends transversely across the traveling grate assembly and includes a cross bar 237 and a series of spaced-apart forward keys 239 separated by spaces 241, and another series of spaced-apart rearward keys 243 separated by spaces 245. Forward keys 239 include forward portion 239a which extends from overlapping portion 23% that overlaps cross bar 237 and is welded thereto by spot-welds 240. Rearward keys 243 include rearward portion 243a which extends from overlapping portion 243b that overlaps cross bar 243 and is welded thereto by spot-welds 244. Keys 239, and 243 are identical in construction and are made of steel eight inches long, 1 3/4 inches wide, and 1/4 inch thick with about 1/8 inch between the side edges 'of adjacent keys. Keys 239, 243, are plug welded to steel cross bar 237 which is 4 inches wide X l/2 inch thickX l2.feet 11 H2 inches across.

The direction of travel of traveling grate 231 is indicated by arrow 251.

Second bar member 235 is similar in construction to first bar member 233 and includes a steel cross bar 253, forward keys 255 which are equidistantly spaced-apart by spaces 257, and rearward keys 259 spaced-apart by spaces 261. Forward keys 255 include forward portion 255a which extends from overlapping portion 255b that overlaps cross bar 253 and is welded thereto by spot-welds 256. Rearward keys 259 include rearward portion 2590 which extends from overlapping portion .259!) that overlaps cross bar 253 and is welded thereto by spot-welds 260.

Rearward keys 243 of first bar member 233 mesh with forward keys 255a of second bar member 235, with first bar member rear keys 243 positioned in forward spaces 257 between second bar member forward keys 255. The second bar member forward keys 255 are positioned in spaces 245 between first bar member rear keys 243. Accordingly, when bar members 233, 235 travel around a sprocket, forward keys 255 clean the spaces 245 and rearward keys 243 clean the slots or spaces 257.

FIG. 2 shows a transverse view in elevation of first bar member 233 with keys 239, 243 being omitted for clarity. Cross bar 237 is attached to three cast iron grate bars 267269 by angle iron clips 271-274 that are bolted to cast iron grate bars 267-269 and welded to cross bar 237.

Also, the ends of cross bar 237 are attached to grate bars 267 and 269 by attachment members 275 having (FIGS. 6-7) body plates 277 mounted on a pair of threaded upstanding studs 279 that are positioned in holes in grate bars 267 and 269 that match with holes in cross bar 237. Countersunk nuts 281 are screwed onto studs 279 to attach cross bar 237 to grate bars 267 and 269.

A hole 283 is formed in body plates 277 to provide for passage of a rod 285 that attaches grate bar 267 to chain links 287. Each grate bar 267-269 is attached to two drive chains. Grate bar 267 is attached (FIG. 4) by passing the rod 285 through the holes in downwardly projecting grate bar lug 289, attachment member 275, downwardly projecting grate bar lug 291, lugs 293 of chain links 287 of drive chain 295, downwardly projecting grate bar lug 297, and a blind hole 299 in grate bar lug 300. After rod 285 has been inserted through said holes, an end piece 301 is mounted by bolts 302 to grate bar 267 to hold rod 285 in place against sliding out of the holes. Drive chain 303 at the other end of cross bar 237 is attached to grate bar 269 in the same manner, with an end piece 304 holding rod 285 in place.

Drive chains 305-308 are attached to the grate bars in a somewhat different manner from drive chains 295 and 303 because there are no removable end pieces 301, 304 that permit the use ofa long rod 285. Instead, drive chains 305-308 are attached in a manner shown in FIG. 5. A short rod 309 is inserted through the holes in grate bar lug 311, chain link lugs 293 and grate bar lug 313. After rod 309 has been so inserted, washers 315 are welded to the ends of rod 309 to keep the rod from slipping back through the holes.

In operation, the assembled series of bar members 233, 235 form a traveling grate 231 that carries the carbonaceous shale and the like through the furnace to burn it and make lightweight aggregate. Then as the bar members travel around the end sprockets, the keys of one cross bar wipe clean the spaces between the keys of the next cross bar to automatically self-clean the traveling grate and prevent and overcome the problems from corrosion and the downward draft of air which cause conventional keys to freeze together.

It will be noted that, during horizontal travel of the grate, the forward keys of the embodiment of FIGS. 1-7 overlap the preceding cross bar and the rearward keys overlap the following cross bar by about l/2 inch. This overlapping gives support to the ends of the keys when the keys are traveling horizontally without interfering with the wiping action that takes place when the grate bars travel around the sprockets.

Turning now to the presently preferred embodiment of the invention illustrated in FIGS. 9-11, there is shown a traveling grate 323 which includes a series of self-cleaning air-flow bar members such as a first bar member 325, and a second bar member 327. First bar member 325 includes a first cross bar channel 329 having flanges 331 connected together by a channel base 333. A series of spaced-apart keys 335 are mounted on channel base 333 and are separated by spaces 337. Keys 335 include forward key portions 335A and rearward key portions 335B connected together by an overlapping key portion 335C which overlaps channel base 333 of cross bar channels 329. Keys 335 are welded to cross bar channels 329 by welds 339 which run along the corners formed between the keys 335 and the channel flanges 33].

Second bar member 327 includes second cross bar channel 343 having flanges 345 connected together by a channel base 347. Keys-349 are mounted on second cross bar channel 343 and are spaced apart so as to provide spaces 351 thereb etween.

The keys 349 include a forward key portion 349A and a rearward key portion 349B connected together by an overlapping portion 349C which overlaps second cross bar channel 343. Keys 349 are mounted on second cross bar channel 343 by welds 353 which run along the corners formed between the keys 349 and the channel flanges 345.

Keys 335 of first bar member 325 are staggered with respect to keys 349 of second bar member 327 so that rearward key portions 3353 are positioned in spaces 351 between keys 349, and forward key portions 349A are positioned in spaces 337 of keys 335.

Chain blocks 357 are welded between channel flanges 331 of first cross bar channel 329 and between flanges 345 of second cross bar channel 343 along welds 359. Chain blocks 357 are provided with holes 361 through which pins are inserted for pivotal attachment to chain links of adrive chain in a manner similar to that shown in FIG. 5.

An outside end plate 363 is welded to the outside end of cross bar channels 329 and 343 along welds 365, and an inside end plate 367 is welded to'the inside end of cross bar channels 329 and 343 along welds 369. Inside end plates have a hole 371 formed therein which admits a rod for attachment to the next transversely adjacent cross bar channel in a manner similar to that shown in FIG. 5 for attachment to a chain link.

Rearward keyportions 335B of first bar member 325 extend into the spaces 351 between forward key portions 349A of second bar member 327 because the keys 335 are staggered with respect to the keys 349. Also, forward key portions 349A of second bar member 327 extend into the spaces 337 between rearward key portions 335B of first bar member 325.

Bar members 325 and 327 are formed in sections which are 3 feet in length with each three foot section having 15 keys mounted thereon. Ten such sections make up a complete transverse bar member. The transverse width of the bar members 325 and 327 may be varied by adding or reducing the number of transverse bar sections. 9

In operation, the assembled series of bar members form a traveling grate 323 which carries the carbonaceous shale and the like through the furnace to burn it and make lightweight aggregate. As the bar members travel around the end sprockets, the keys of one bar member wipe clean the spaces between the keys of the next bar member and this automatically self-cleans the traveling grate and permits the passage of air there through. This self-cleaning prevents and overcomes the problem of corrosion and prevents the keys from freezing together and breaking.

The bar members 325 and 327 are of all steel construction and the use of cast iron, which has given trouble in the past, has been eliminated.

During horizontal travel of traveling grate 323, the forward key portion rests on the preceding bar member and the rearward key portion rests on the following bar member.

The embodiment of FIGS. 9-11 uses half the number 7 of keys as the embodiment of FIGS. l'-8 because the keys in FIGS. 9-1 1 have'both forwardly and rearwardly extending portions.

The bar members 325 and 327 are constructed in three foot sections and the inside end plates 367 are 7 provided with the holes 371 that receive a rod for connecting the bar member section to the transversely adjacent section. Accordingly, the traveling grate may have various desired belt widths formed in multiples of the three foot bar member sections, such as 27 feet.

A pair of chain 'blocks 357 are used to attach the cross bar channels to each conveyor chain, and two pairs of blocks 357 are provided for each three-foot bar member section to two conveyor chains.

Cross bar channels 329 and 343 are provided with slots or notches for easier positioning and insertion of the chain blocks 357.

The welds 339 and 353 in the embodiment of FIGS. 9 to 11 are made between the keys and the channel flanges and this provides a good weld one and one-half inches long. The bar members of FIGS. 9-1 1 are of all welded construction which eliminates the use of the nuts and bolts required in the embodiment of FIGS. 1-8.

The steel grate bars are much less expensive than conventional grate bars made of cast iron. Steel is not generally used in fabricating traveling grates and cast iron has generally been preferred because of the high temperatures involved in furnaces, especially in standard boilers when the fire is banked with the grate stopped. However, it is feasible to use steel in fabricating my traveling grates because the grate is always moving, is cooled with steam in the ignition chamber, and is provided with a sealing layer 206 of shale.

In shutting down the furnace, the oil burners are turned off, and the traveling grate is run all the way through the furnace to discharge all fire and hot coals from the furnace before grate movement is stopped. Also, fans are kept on for at least 6 hours to cool the furnace. It normally takes 24 hours for the ignition chamber to cool off because of the tremendous heat retained in its refractory walls.

I claim:

1. In a traveling grate assembly for conveying carbonaceous shale and the like through a furnace to make lightweight aggregate, a first self-cleaning air-flow bar member extending transversely across the grate assembly, said first bar member including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, a second self-cleaning air-flow bar member extending transversely across the grate assembly, said second bar member including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, the rearwardly extending key portions of said first bar member meshing with the forwardly extending key portions of said second member with said first member rear key portions positioned in spaces between said second bar member forward key portions and said second member forward key portions positioned in spaces between said first bar member rear key portions, whereby the key portions of one cross bar clean the spaces between the key portions of the other cross bar when said grate assembly travels around a sprocket.

2. The apparatus of claim 1, including keys formed by said forward and rearward key portions being connected together by an overlapping key portion which overlaps its cross bar, the keys of the first cross bar being staggered with respect to the keys of the second cross bar.

3. The apparatus of claim 2, said bar member including a channel with a pair of flanges connected by a base, said keys being connected to the channel by welds running along the corners formed between the keys and the channel flanges.

4. The apparatus of claim 3, including chain blocks welded between the channel flanges and having holes for pivotal attachment to chain links of a drive chain.

5. The apparatus of claim 1 including a furnace chamber through which said grate assembly travels,

means for igniting said carbonaceous shale, and means for forcing gases downwardly through said grate assembly and said bar members.

6. The apparatus of claim 1 wherein said cross bars are made of steel, and including forward and rearward keys formed by said forwardly and rearwardly extending key portions being extensions of overlapping key portions which overlap their cross bars, the rearward keys of the first cross bar being staggered with respect to the forward keys of the second cross bar, and said overlapping key portions are welded to the cross bars.

7. The apparatus of claim 1, said cross bars being made of steel and said keys being welded thereto, said bar members having a plurality of transverse grate bars,

means attaching said cross bars to said grate bars, a plurality of drive chains having a multiplicity of chain links, and pivot means pivotally attaching said grate bars to said chain links.

8. The apparatus of claim 7, said means attaching said cross bars to said grate bars comprising iron clips welded to the cross bars and bolted to the grate bars, attachment members having plates mounted on upstanding studs that pass through matching holes in said grate bars and cross bars, and nuts that screw onto said studs to hold the grate bars and cross bars together.

9. The apparatus of claim 7, said chain links having depending lugs with holes therein, said grate bars having depending lugs with holes therein that match the chain link lug holes, said pivot means including rods that pass through said lug holes.

10. The apparatus of claim 1 wherein, during straight-line travel of said bar members, said forward key portions of said second bar member overlap said frist cross bar, and the rearward key portions of said first bar member overlap said second cross bar.

a: a s s v 

1. In a traveling grate assembly for conveying carbonaceous shale and the like through a furnace to make lightweight aggregate, a first self-cleaning air-flow bar member extending transversely across the grate assembly, said first bar member including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, a second selfcleaning air-flow bar member extending transversely across the grate assembly, said second bar member including a cross bar and a series of spaced key portions extending forwardly and rearwardly therefrom, the rearwardly extending key portions of said first bar member meshing with the forwardly extending key portions of said second member with said first member rear key portions positioned in spaces betweeN said second bar member forward key portions and said second member forward key portions positioned in spaces between said first bar member rear key portions, whereby the key portions of one cross bar clean the spaces between the key portions of the other cross bar when said grate assembly travels around a sprocket.
 2. The apparatus of claim 1, including keys formed by said forward and rearward key portions being connected together by an overlapping key portion which overlaps its cross bar, the keys of the first cross bar being staggered with respect to the keys of the second cross bar.
 3. The apparatus of claim 2, said bar member including a channel with a pair of flanges connected by a base, said keys being connected to the channel by welds running along the corners formed between the keys and the channel flanges.
 4. The apparatus of claim 3, including chain blocks welded between the channel flanges and having holes for pivotal attachment to chain links of a drive chain.
 5. The apparatus of claim 1 including a furnace chamber through which said grate assembly travels, means for igniting said carbonaceous shale, and means for forcing gases downwardly through said grate assembly and said bar members.
 6. The apparatus of claim 1 wherein said cross bars are made of steel, and including forward and rearward keys formed by said forwardly and rearwardly extending key portions being extensions of overlapping key portions which overlap their cross bars, the rearward keys of the first cross bar being staggered with respect to the forward keys of the second cross bar, and said overlapping key portions are welded to the cross bars.
 7. The apparatus of claim 1, said cross bars being made of steel and said keys being welded thereto, said bar members having a plurality of transverse grate bars, means attaching said cross bars to said grate bars, a plurality of drive chains having a multiplicity of chain links, and pivot means pivotally attaching said grate bars to said chain links.
 8. The apparatus of claim 7, said means attaching said cross bars to said grate bars comprising iron clips welded to the cross bars and bolted to the grate bars, attachment members having plates mounted on upstanding studs that pass through matching holes in said grate bars and cross bars, and nuts that screw onto said studs to hold the grate bars and cross bars together.
 9. The apparatus of claim 7, said chain links having depending lugs with holes therein, said grate bars having depending lugs with holes therein that match the chain link lug holes, said pivot means including rods that pass through said lug holes.
 10. The apparatus of claim 1 wherein, during straight-line travel of said bar members, said forward key portions of said second bar member overlap said frist cross bar, and the rearward key portions of said first bar member overlap said second cross bar. 